1. Field of the Invention
This invention relates to an amputated part holding apparatus which is used to make a mould of an amputated part of a human body for production of a prosthesis, and to enable virtual experience of putting on a prosthesis, and a method for making a mould for an amputated part of a human body.
2. Description of the Related Art
An artificial limb is generally used for an amputee who has had a leg or arm amputated. In production of such artificial limbs, it is necessary to ensure fitness of an artificial limb to the amputated part. Accordingly, the production of an artificial limb starts with making an accurate mould of an amputated part, and followed by the step of carefully making an artificial limb according to the mould. Such mould is made because of the fact that: 1) it takes a long time to make a prosthesis; and 2) an amputee cannot attend throughout the production processes of the prosthesis.
The process of making a mould is as follows. At first, an amputated part and its adjoining part are wound with a gypsum bandage which has not yet hardened, and the outside of the gypsum bandage is kept pressed until the hardening is completed. The hardening of the gypsum bandage takes about 5 or 10 minutes. After being hardened, the gypsum bandage is removed from the body, and is used as a mould or female model to be filled with gypsum. After the hardening of the filled gypsum is completed, the female model is blocked off to thereby produce a male model of the amputated part.
As mentioned above, the making of a female model or mould of an amputated part is the starting point of the production of an artificial limb. Accordingly, the female mould greatly influences the finished quality of an artificial limb as final product. If the mould is poor, the resulting artificial limb dose not only fit the amputee, but may also cause a pain to the amputee. As an amputated part is especially sensitive, much care is required for the making of a mould.
Because an excellent skill is required for making of a mould, it is not easy to obtain a satisfactory mould. For example, the tightness of wound gypsum bandage or the pressure against the gypsum bandage during hardening affects the resulting mould. Moulds made by an immature artisan are usually almost inadequate.
In view thereof, an amputated part holding apparatus 68 using air pressure has been proposed as shown in FIGS. 15A and 15B. Specifically, an amputated part 60 wound with a gypsum bandage 64 is inserted into an inner space 62 defined by a silicone tube 61 having an air chamber 63. Pressurized air is filled in the air chamber 63 to uniformly press the outside of the gypsum bandage 64 during the period of hardening the gypsum bandage 64. The air pressure in the air chamber 63 is numerically controlled by a pressure gauge to regulate the pressure against the outside of the gypsum bandage 64.
Also, an amputated part holding apparatus 69 shown in FIG. 16 is proposed in JSPO Journal, Vol. 14(2), p 178, published by Japanese Society of Prostheses and Orthoses on Apr. 1, 1998. The amputated part holding apparatus 69 includes a hard cylindrical casing 65 and a flexible tube 66 of silicone rubber to define an air chamber 67 therebetween. An inner space is defined by the flexible tube 66. In the amputated part holding apparatus 69, similarly to the amputated part holding apparatus shown in FIG. 16A, pressurized air is filled in the air chamber 67 to press the outside of a gypsum bandage 64 wound on an amputated part 60 which has been inserted in the inner space defined by the flexible tube 66.
These prior art amputated part holding apparatuses 68 and 69 utilize pressurized air to give uniform pressure to the outside of the gypsum bandage, and do not require the high skill. In the case of making a mould of an amputated leg by the above-mentioned amputated part holding apparatuses, however, an amputee is required to seat on a chair. The seated posture is disadvantageous to make a mould of an amputated leg. This is because of the fact that: 1) the amputated part changes in the aspects of shape, bone protrusion, and muscle tension between the standing posture in which the amputated leg receives the body weight of the amputee and the seating posture in which the amputated leg receives no weight; and 2) the prosthesis must work in the standing posture such as walking.
It could be seen that in even these amputated part holding apparatuses 68 or 69, mould making is possible in the standing posture. However, these amputated part holding apparatuses 68 and 69 do not have any support to keep the amputated leg in standing posture. The gypsum bandage is pressed by the pressurized air, but cannot be kept from moving down due to the body weight. To prevent the amputated leg from sinking into the tube, consequently, a support member or device is additionally required to support the body weight of the amputee. However, even if such a support member is provided, actual conditions of the amputated leg cannot be attained, consequently making a mould reflecting a bone protrusion and muscle tension different from the actual standing posture conditions.
It may be possible to hold the body weight by increasing the air pressure in the air chamber. However, such higher pressure changes the shape of the amputated leg and gives undesirable pain to the amputee. This is not adequate for making a mould.
In addition to the above-mentioned prior art apparatuses, another amputated part holding apparatus shown in FIGS. 17A to 17C is proposed in JSPO Journal, Vol. 16(Supplement), p 114-115, published by Japanese Society of Prostheses and Orthoses on Sep. 1, 2000, and PO Academy Journal, Vol. 9(2), p 109-110, published by Japanese Academy of Prosthetists and Orthotists on September, 2001. This amputated part holding apparatus enables mould-making with the body weight being loaded.
This amputated part holding apparatus 70 includes a base member 73, a support channel 72 fixedly mounted on the base member 73, a slider block 74 slidably attached on the support channel 72, and a holder ring 71 fixedly attached on the slidable block 74. An amputated leg to be moulded is inserted into the holder ring 71. The slider block 74 is tightly stayed at a desired position of the support channel 72 by a fastening screw.
The amputated part holding apparatus 70 is used in the following way. At first, a gypsum bandage 64 is wound over an amputated part of a leg 60 in several times. After the gypsum bandage 64 reaches a predetermined hardness, the leg 60 covered with the gypsum bandage 64 is inserted into the holder ring 71, and the body weight is supported by the holder ring 71 until the gypsum bandage 64 attains a predetermined hardness. It should be noted that before applying the body weight, the inner part of the gypsum bandage 64 is required to be moldable. If the inner part of the gypsum bandage 64 should be hardened before applying the body weight, the finished mould has an inner wall not reflecting the actual state of the amputated part in the standing posture. On the other hand, if the outside of the gypsum bandage 64 is not firmly hardened, the gypsum bandage 64 cannot be stayed by the holder ring 71.
Utilizing the nature that the hardening rate of gypsum depends on the temperature, accordingly, gypsum prepared with cold water is used for the inner part 64a of the gypsum bandage 64 and gypsum prepared with hot water is used for the outer part 64b of the gypsum bandage 64 so that the outer part 64b hardens faster than the inner part 64a. 
As mentioned above, the apparatuses 68 and 69 need not the excellent skill, but cannot perform molding in the standing posture, and cannot consequently make a good female mould having an inner wall reflecting the conditions of an amputated leg in the standing posture. The apparatus 70 makes it possible to make a female mould having an inner wall reflecting the conditions of an amputated leg in the standing posture, but requires an excellent skill for the operator.